The whole idea is that you have a straightforward visual clue of what the selected database is. This way, when you work with the application tabs (Table, Data, Query...) you can avoid doing stuff with the wrong piece of data. The concept of current database is inherent to SQL.

I admit that HeidiSQL could also change foreground colour to match background colour (if background luminosity is less than 50% it'd make sense to use a light foreground) and it doesn't, but the feature itself is quite well thought IMHO.

If you open HeidiSQL via command line host/user/password, you are not using a stored session, therefore nothing else is stored for the next time you do that. Just use a session (-d=xyz) or do not use the command line options at all if you expect session settings to be stored.

Regarding the color to DB Session behaviour. I've found that the old behaviour, in which the whole panel would switch to the current session color, to be better than the current multi-colored one.

When I had the old behaviour, I would never mix my DBs up, but since moving to the new behaviour, it is quite common to mix up my connections (DEV/TST/PRD) because of missing out on the "grayed" out fonts.

As some people may prefer to have the current behaviour, would it be possible to have both the old and new behaviour through a preferences switch/option?